1. Field of the Invention
The present invention relates to a light receiving device and a method of manufacturing the light receiving device, and more particularly, to a light receiving device including a transparent electrode and a method of manufacturing the light receiving device.
2. Description of the Related Art
In order to maximize energy efficiency of a light receiving device such as a solar cell or a photodiode which receives light, a transparent electrode having excellent transmittance characteristics with respect to light in a UV wavelength range as well as light in a visible wavelength range is required to be developed.
Currently, an ITO (indium tin oxide) transparent electrode is widely used as a transparent electrode of a light receiving device. However, the ITO transparent electrode is not in good ohmic contact with a semiconductor layer having a function as a photoelectric conversion layer which absorbs light to generate electric energy. Therefore, there is a problem in that electricity generation efficiency of the light receiving device is decreased. Particularly, since the ITO which is widely used in the light receiving device has high transmittance loss in a UV wavelength range of 400 nm or less, the ITO transparent electrode has a limitation in application to a UV light receiving device.
In order to solve the problem, a transparent electrode capable of allowing current to be smoothly injected by decreasing contact resistance between the transparent electrode and the semiconductor layer and having high transmittance characteristics with respect to light in the entire range needs to be developed.
Although various researches have been made in order to solve the above-described problems, a transparent electrode capable of implementing high transmittance and high conductivity with respect to light in a UV wavelength range has not been developed. This is because conductivity and transmittance of a material has a trade-off relationship. Since a material having as high transmittance as it can be used in a UV wavelength range has a large band gap (larger than the band gap (3.4 eV) of ITO), the material has too low conductivity to be used as an electrode and is not in ohmic contact with a semiconductor material. Therefore, it is impossible to use the material as an electrode.
Therefore, in order to implement the light receiving device such a high-efficiency solar cell or a high-efficiency photodiode capable of being used for the light in a UV wavelength range as well as the light in a visible wavelength range, a transparent electrode having high transmittance characteristics with respect to light in the entire wavelength range and having high conductivity characteristics so as to be in ohmic contact with a semiconductor layer needs to be developed.